The main purpose of this study was to examine the relationship between excellence-oriented leadership and the improvement of educational standards, with the mediating role of organizational culture in upper secondary schools in Mahabad County. This research is applied in terms of purpose and descriptive-correlational in terms of methodology, and it was conducted within the framework of structural equation modeling (SEM). The statistical population consisted of all upper secondary school teachers in Mahabad County, totaling 645 individuals. The sample size was estimated to be 240 participants using Cochran’s formula, and simple random sampling was employed. Data were collected using three standardized questionnaires, including the Educational Standards Improvement Questionnaire (Kobriaei & Roudbari, 2005), Denison Organizational Culture Questionnaire (2006), and Bass and Avolio’s Excellence-Oriented Leadership Questionnaire (2006). The collected data were analyzed using structural equation modeling with SmartPLS 4 and SPSS version 30 software. The results indicated that excellence-oriented leadership has a positive and significant effect on the improvement of educational standards. This effect was also confirmed indirectly through organizational culture (t > 1.96, p < 0.05). Overall, the findings suggest that organizational culture plays a significant mediating role in strengthening the impact of excellence-oriented leadership on the quality and standards of education. Therefore, strengthening and developing organizational culture in schools can provide a suitable context for enhancing the effectiveness of excellence-oriented leadership